Oxidation inhibitor



Patented June 17 1930 UNITED STATES.

REGINALD soo'r'r DEAN, or OAK OPAR-K, ILLINOIS, ASSIGNOR To wnsrnmr Emerald PATENT OFFICE COMPANY, INCORPORATED, 013 NEW YORK, N. Y., A CORPORATION OF NEW YORK OXIDATION INHIBITOR No Drawing.

'In the heat treatment of some types of 5 articles, it is'often desirable to obtain'as complete protection against oxidationas possible. For example, tools having carefully ground edges or dies possessing delicately carved surfaces, are very easily ruined by oxidation during heat treatment.

The method of manufacturing such dies or tools is to form them from untreated and unhardened steel and then to heat-treat'them to cause a hardening of'the finished article. During the hardening treatment, it is desirable to avoid conditions which will make it necessary to do any work on the article after it has been hardened. For example, if the articleis oxidized to any extent during the hardening thereof, it is necessary to re-grind or re-touch the oxidized portions, and this may be a diflicult and expensive operation. Moreover, if the article is very delicately made-even a small amount of oxidation will sometimes ruin it, since it may be impossible to repair the damage which has been done.

Various methods have been employed .for, the purpose of protecting surfaces of such articles during heat treatment. A method which has, been employed frequently 'is'to sprinkle dry boric oxide on the surface to be protected. This material fuses at a comover the surface in such a way as to prevent contact of the surface with the oxygen of the air.

This method is not entirely desirable because the boric oxide will usually sputter and.

cra off in spots when it is heated. In order to prevent this, it is necessary to use a great bulk of the protecting material so as to. make a thick layer overthe whole article.

Even this thick layer does not always provide Application filed May 12, 1924. SerialNo. 712,549.

to use as small an amount of it as is safe and practicable. One object of this invention is to provide an improved method for protecting material during heat treatment.

Another object of this invention is to pro- Vide a method for applying a uniform coating of a fusible material to the surface of an article to be heat-treated.

A further object of thisinvention is to produce a solution'consisting of a fusible material in a volatile solvent and adapted to be applied to a metallic surface for the purpose of protecting said surface during heat treatment.

The principal feature of this invention is forming a suspension of fusible material in a volatile solvent, applying the resulting solutionto a metallic surface andallowing said solution to dry before heating the metallic surface. 5

Other objects and features of the invention will appear more fully in the following de- V 1s necessary to employ, therefore, awaterfree solid material and a non-aqueous liquid.

However, to obtain a true suspension a very small amount'of water is preferably present. One manner in which this water may be introduced will be explained hereinafter. As stated, the solid material employed is preferably entirely free from water, even water of crystallization. Boric oxideis a dry material and can, therefore, be used, but a fusible salt, for instance, containing water in chemical combinatoin must be thoroughly de-hydrated before it is suitable for use.

The carrier liquid may be any non-aqueous,

\ dride and parts, by'weight, of carbontetrachloride have been found to give good results. I A peptizing agent is then added to the mixture for the purpose of facilitating carbon-tetrachloride and an aqueous peptizing agent.

3. Anew composition of matter compristhe formation of a colloidal solution. A

small amount of aqueous alcohol, employed in the proportion of about 1% of the mixture, is found to be a good peptizing agent for use with boric oxide, or boric anhydride and carbon-tetrachloride. Chemically pure or absolute alcohol is not desirable for this purpose, however, on account of its deficiency 1n water. of water is necessary to obtain a suspension of the boric oxide in the carbon-tetrachloride, and the best way of adding this water seems to be in the form of an impurity in alcohol.

A composition formed in this manner will remain in suspension for about six months if left quietl and even if the boric oxide does settle to t e bottom of the container, it can be made to re-enter into suspension by agitating the container.

This solution can be eithersprayed, painted or dipped or otherwise applied to the surface which it is desired to protect. When the carbon-tetrachloride evaporates it leaves a thin film of boric oxide covering the entire surface of the article to be protected. Vertical surfaces receive the same coating as horizontal surfaces and the boric oxide applied in this manner is not dislodged or shaken off by ordinary handling. When the articles to be treated are coated in the manner just described the boric oxide film melts when heated and forms a thin fused film on the entire surface. This film will not sputter or crack; or flow in such a way as to leave vertical surfaces bare and unprotected. The most delicately formed surfaces may be sprayed with the solution and positive protection afforded to every little crevice or edge so as to render unnecessary any touching up after the completion of the heat treatment.

As indicated above a small amount It is to be understood that the invention is not restricted to the use of a solution of boric oxide, carbon-tetrachloride and alcohol in the manner described and the invention is limited 7 only by the scope of the appended claims.

What is claimed is:

1. An oxidation inhibitor comprising boric anhydride, carbon-tetrachloride, and a small amount of aqueous alcohol.-

2. -A new composition of matter comprisinga stable suspension of boric anhydride, 

